Lifting-magnet controller.



J P. MOTZ.

LIFTING MAGNET CONTROLLER.

nruommx rILnn no. 11, 1901.

960,995. Patented June 7, 1910.

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ATTORNEY UNITED STATES PATENT OFFICE.

JACOB F. MOTZ, OF PITTSBURG, PENNSYLVANIA ASSIGNOR TO THE ELECTRIC CON-TROLLER AND SUPPLY COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

LIFTING-MAGNET CONTROLLER.

To all whom it may concern:

Be it known that I, Jaooa F. Mo'rz, a citizen of the United States,residing at Pittsbur in the county of Allegheny and State ofIennsylvania, have invented or discorered new and useful Improvements inLifting-Magnet Controllers, of which the following is a specification.

In the operation of lifting magnets, I have found that when the currentis quickly broken, a high inductive voltage is generated in the magnetwindings. This voltage I have measured and found it to be several timesthe normal voltage with which the mamet is excited. The presence of thishigh volta e I have found puts a strain on the'insulatlon of the magnetwinding and on the wires going to the magnet. In the past it has beenthe practice to introduce a resistance in series with the magnet beforeopening its circuit. This decreases the current in the magnet and thisreduces the inductive voltage enerated when the circuit is finallyopened. To introduce resistance in series with a magnet as describedabove, requires the use of some form of controller having a rather largenumber of steps and a bank of resistance with a corres onding number ofsub-divisions. Even tien the purpose of the controller can be defeatedby a careless operator who may open the circuit of the controller soquickly that the current cannot be reduced to its proper value (due tothe inductive effect of the magnet) and a severe flash will occur in thecontroller and a high inductive voltage be generated in the magnet. Toovercome these difficulties, I have devised for magnets a controllerthat is independent of the speed, with which the operator moves thecontroller. This controller is simpler and smaller than a controllerwhich inserts resistance in series with the windin of a magnet beforeopening the circuit of t e same.

Referring to the drawings, Figures 1 and 2 are diagrammatic views showmtwo of the many forms which my invention may assume.

Referring now to Fig. 1, I use a master switch or controller D and anelectro-magnetically operated switch E. To ener ize the magnet, thehandle of the switch is moved to the right so that the blade 2' makesconnection with the contacts j and 7c and leaves connection with contactZ. Current Specification of Letters Patent.

Application filed December 17, 1907.

Patent-ed June 7, 1910.

Serial No. 406,851.

will then flow from plus line through the coil m of switch E, thecontact A of the switch D, the blade 7'. and the contact j to thenegative main. This will energize the coil m of the switch E and causethe arm a to make connection with the contact 0, which is joined to thepositive main through the blow-out coil I. Current will then flow asfollows: from the positive main through the contact 0, the arm n, andthe magnet M to the negative main. To deenergize the magnet, the handleof the switch 1) is placed m the position shown and the magnetdischarges as follows: from the terminal g to the lower terminal of theswitch E, through the resistance It to the contact Z of switch D,through the blade 5 to the contact j, and thence to the terminal It ofthe mzwnet. It is to be noted that contacts II: and l overlap so thatthe resistance R is inserted before the switch E is opened. Switch E canbe made to open quickly and may have the blow-out coil P attached toextinguish quickly any are formed at its contacts. Thus it will have alonger life than a switch with the time of opening dependent on theoperator, who ma cause it to open slowly and the arc to en ure for alonger time.

Still another arrangement of my invention is shown in Fig. 2. In thisarrangement I use two electro-magnetically controlled switches, a masterswitch or controller, and a bank of resistance. To energize the magnetthe handle of switch F is moved to the right. so that the blade 8 makesconnection with terminals t and u. Current then flows as follows: fromthe positive main through the coil 1 of the switch H, the contact a ofswitch F, the blade .9, and the contact If to the ne ative main. Thiscloses the switch II and the current flows through the magnet asfollows: from the positive main through the contact w of the switch H,the arm on, and the magnet to the negative main. To deenergize themagnet, the handle of the switch H is moved to the left until it assumesthe position shown, when the blade 8 makes connection with the contactst and v. The current then flows from the positive main through the coild of the switch G, the contact a) of the switch F, the blade 8, and thecontact t to the negative main. The magnet then discharges as follows:from the terminal 9 through the resistance R, the arm a of the switch G,

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the contact 2 to the terminal h of the magnet.

In both of the figures and description, I have shown and sioken of thecontacts on the master controller or switch as overlap- )ing. It isohvious that this is not ahsoutely necessary.

I. The combination of a lifting magnet having therein au energizingwinding, a magnetically operated switch for connecting the winding ofthe lifting magnet to a source of current. a hunk of resistance, and amanually operated controlliu switch, said controlling switch beingprovided with contacts whereby, when it is moved from its till-position,the winding of said magnetically operated switch is ener ized and thecircuit closed throu h the winding of said littin magnet, am when saidcontrolling switch is moved to its otI-position. the said hunk ofresistance is connected across the terminals of the winding of saidlifting ma net through certain of the contacts of sait controllinswitch.

2. The combination of an electric apparatus having an inductive winding,a magnetically-o rated switch connecting a source of e ectric energy tothe said winding, a resistance, and a controlling handoperated switchhaving contacts arranged to close a circuit across the line wherehy.when it. is moved from its oil-position, the winding of thennignetically operated switch is energized and circuit. closed throughthe said inductive winding, and when said controlling switch is moved toits otY-position, the said resistance is connected across the terminalsof the said inductive winding.

3. The combination of an electric device having an inductive winding, amagneticalLv-operated switch connecting a source of euergv to the saidwinding. a resistance, a second magnetically-operated switch havingcontacts arranged to connect. the said inductive winding and theresistance in a closed circuit, and a hand-operated switch havingcontacts for closing the first magnetically-operated switch to energizethe said electric device and for closing the second magneticallyoperated switch to connect. the said winding and resistance in saidclosed circuit when the contacts of the first. magnetically operatedswitch are ogcued.

bigned at Pittsburg, Ia., this 9ti day of December, 1907.

JACOB F. MOTZ.

Witnesses:

F. N. Banana, ANNA R. Bnam'.

